Aircraft must be serviced from time to time, when they breakdown or for periodic maintenance. As aircraft are worked on, mechanics must pay attention not only to the service work they perform, but also to the parts and surfaces of the aircraft. If the mechanic is not careful to avoid certain areas on an aircraft, damage may result. Damage from a paint scratch to a structural failure could be caused by the mechanic. This is especially so when a mechanic performs regular periodic maintenance on an aircraft.
When aircraft mechanics attempt to provide a makeshift barrier between themselves and the aircraft to prevent accidental damage, they encounter a number of problems caused by using a barrier material that is not suited for the job of protecting an aircraft from the mechanic. Often, simple blankets are used as a barrier between a mechanic and an aircraft. These blankets are not effective for a number of reasons. The blanket size can be too big or too small relative to the surface to be protected. If too big, the blanket can act as an impediment to the mechanic's work, slowing him down and/or creating a safety hazard for the mechanic by snagging tools or becoming entangled in an aircraft's working parts. If a blanket is too small, then not enough protection is afforded the aircraft, and misplaced tools could foul operating surfaces and other critical operating parts.
One of the most serious and common problems associated with using simple blankets as barriers occurs when a blanket is thrown over aircraft surfaces that have various load bearing capabilities at different locations on those surfaces. Aircraft have a number of large flat surfaces upon which mechanics may stand in order to gain access to and work on the aircraft's engines, rudders and other systems vital to its proper and safe operation. Flat aircraft surfaces such as engine fairings, wings and tails generally have portions of their surfaces which may safely bear a mechanic's weight. More importantly, the above mentioned surfaces all have portions which may not safely bear a mechanic's weight. These areas are designated with a "no-step" or similar indication.
Furthermore, the various flat surfaces on a specific make and model of aircraft, e.g., an engine fairing or wing on a Cessna Citation, are differently shaped from the analogous flat surfaces on another make and model of aircraft, e.g., an engine fairing or wing on a Piper Cherokee. To compound the problem, the "no-step" areas on each surface vary according to the make and model of aircraft.
When simple blankets are used as a protective barrier between the mechanic and the aircraft, the "no-step" indication is obscured so that a mechanic has nothing to rely on other than memory to tell him which areas of the flat surface are safe to bear weight upon. One misstep by the mechanic using a simple blanket for protection may lead to a structural failure that may be expensive to fix and potentially dangerous to the aircraft's passengers if the failure goes unnoticed and not corrected.